Raised floor with clamped panel support

ABSTRACT

A raised floor structure supports electronic equipment units and provides space for electric cabling thereunder. A plurality of spaced parallel beams are supported above a subfloor by vertically adjustable pedestals. A first group of freely insertable and removable rectangular floor panels, each resting on a pair of adjacent beams, forms equipment unit access areas. A second group of rectangular floor panels, each having its underside rigidly attached to a pair of adjacent parallel beams, forms a base for equipment units. The rigidly attached floor panels provide horizontal structural support for the spaced parallel beams.

[ Dec 9, 1975 United States Patent [191 Cauceglia et al.

[54] RAISED FLOOR WITH CLAMPED PANEL 3,789,557 2/1974 52/126 FOREIGNPATENTS OR APPLICATIONS SUPPORT t a m w m 1c .1 M J .m ml m m 4 m 3 r 50 6 w .mt n 3 me a8 A 2 EV, m 9 Mr 8 0 6 "U PA ;H ma mam fig wwmm CV wumC M w 6% m d as mm fl m mCu .afi um m WEN a uf WWLo & r m n e V n I l. 5U

[57] ABSTRACT A raised floor structure supports electronic equipmentunits and provides space for electric cabling thereun- [73] Assignee:Bell Telephone Laboratories,

Incorporated, Murray Hill, NJ.

July 24, 1974 Appl. No.: 491,343

[22] Filed:

der. A plurality of spaced parallel beams are suported above a subfloorby vertically adjustable pedes- [52] US. Cl. 52/126; 52/263; 52/220 p 351 Int. E04F 13/08 A first group freely "Senable and removablerectangular floor panels, each resting on a pair of ad- [58] g 629 592593 541 jacent beams, forms equipment unit access areas. A 6 secondgroup of rectangular floor panels, each having its underside rigidlyattached to a pair of adjacent par- References Cited allel beams, formsa base for equipment unlts. The rig- UNITED STATES PATENTS idly attachedfloor panels provide horizontal structural support for the spacedparallel beams.

3,150,748 52/126 x 3 316,680 Chrastek.............,.................52/l26 11 Clams 6 D'awmg Flgures Sheet 1 0f 3 3 92,37

U.S. Patent Dec. 9 1975 US. Patent Dec. 9 1975 Sheet 2 of3 3,924,370

FIG. 2

Sheet 3 of 3 3,924,370

U.S. Patent Dec. 9 1975 FIG. 5

BACKGROUND OF THE INVENTION Our invention relates to raised floorconstruction adapted to support equipment units requiring spacethereunder for cabling and ancillary apparatus, and

more particularly to raised floor structures having a plurality ofpanels supported on a pedestal arrangement over a subfloor.

In communication and computing facilities and elsewhere, theinterconnection of electronic equipment units involves complexelectrical cabling, piping and duct work between the equipment units. Anelevated floor overlying the existing floor structure can be employed toprovide space for cabling and other apparatus underneath the electronicequipment units in a manner that avoids interference with equipmentunits, interference with equipment operation and maintenance, accidentaldamage, and hazards to operating personnel. Such floor structuresinclude removable sections for inspection and maintenance of the cablingand apparatus between the subfloor and the raised floor on which theequipment units are mounted.

In one type of priorly known raised floor construction, a plurality ofrectangularly dimensioned, rigid, lightweight panels are placed over arectangular grid of supporting beams. The beams, in turn, are attachedto the subfloor by means of periodically spaced pedestals. Each panel isfreely insertable and removable so that access to areas underneath theraised floor is available. The interconnection of the orthogonal beams,however, is complex and expensive owing to the requirement that theraised floor panels form a smooth, flat surface.

Another type of known floor panel construction utilizes a supportingstructure of parallel beams running the length of the floor in onedirection. Each beam is mounted on a plurality of pedestals, whichpedestals rest on the subfloor. Each rectangularly dimensioned floorpanel is spanned between a pair of adjacent beams and a continuousraised floor is formed by sideby-side panel placement. To preventshifting of the parallel beams, the ends of the floor panels overlyingthe beams are rigidly attached to the beams by a bar structure runningthe beam length. In this manner, the raised floor is fully supported andthe floor panels form an integral part of the support structure. Theconnection between the floor panels and the beams, however, increasesthe difficulty of removal of an individual panel for purposes ofinspection or maintenance. Additionally, the structure of the floorpanel ends, the beams, and the overlying bar are relatively complex inorder that the junction of the floor panel ends and the overlying barconform to the smooth surface of the raised floor. Further, the metallicbar structure provides an unwanted electrical path to ground through theraised floor structure.

It is an object of the invention to provide an improved raised floorsupported on a parallel spaced beam structure and having freelyinsertable and removable individual floor panels for access to the spacebeneath the raised floor.

It is another object of the invention to provide an improved raisedfloor structure having a plurality of spaced parallel beams which areprevented from shifting by attachment of selected floor panels to thebeams adjacent thereto.

It is yet another object of the invention to provide an improved raisedfloor structure having selected floor panels laterally supporting thespaced parallel beams and other panels freely insertable and removableto provide ready access to the space beneath the raised floor.

It is yet another object of the invention to provide an improved raisedfloor structure for supporting a plurality of equipment units whereineach laterally supporting floor panel underneath equipment has itsunderside rigidly clamped to the pair of adjacent beams on which itrests.

It is yet another object of the invention to provide an improved raisedfloor structure for supporting a plurality of equipment units whereinthe laterally supporting floor panels are arranged in rows underlyingthe equipment units. Freely insertable and removable floor panels arearranged in rows adjacent to the laterally supporting floor panelswhereby access to the space beneath the raised floor and the laterallysupporting panel clamping arrangements is obtained.

It is yet another object of the invention to provide an improved raisedfloor structure adapted to protect electronic equipment mounted thereonfrom overturning.

SUMMARY OF THE INVENTION The invention is directed to a raised floorstructure for supporting equipment above an existing floor whileallowing space beneath the equipment for cabling, pipes and otherancillary apparatus. A plurality of spaced, parallel beams are supportedon subfloor mounted, vertically adjustable pedestals. Each of a firstgroup of rectangularly dimensioned floor panels spans between adjacentparallel beams and rests thereon in nonequipment areas. Each of a secondgroup of rectangularly dimensioned floor panels spans between adjacentparallel beams and rests thereon underneath equipment units. Each firstgroup panel is freely insertable and removable from adjacent beams, buteach second group panel has its underside portion thereof rigidlyattached to the beams on which it rests whereby the second group panelsprovide transverse support for the parallel beam structure.

According to one aspect of the invention, the underside of each adjacentpair of said second group panels is attached to the common baseunderlying said panels by a removable clamp connected to the undersidesof said pair of second group panels and to the common beam. Access tosaid clamp is obtained by removal of an adjacent first group panel.

According to another aspect of the invention, the second group panelsare placed in rows running transverse to the direction of the parallelbeams, said rows of second group panels underlying equipment units.

According to yet another aspect of the invention, selected first grouppanels and each second group panel includes an apertured venting sectionwhich permits air flow adjacent to said equipment units.

angularly dimensioned, rigid but lightweight raised floor panels. Eachbeam is mounted on a plurality of vertically adjustable pedestals, whichpedestals rest on the subfloor. The raised floor is divided intosections that underlie and support electrical equipment units and intosections used by operating personnel for access to said equipment units.In the access sections, a plurality of first dimensioned rectangularfloor panels are placed side by side to form a flat surface. Each firstdimensioned floor panel spans between and rests on adjacent parallelbeams and is juxtaposed with adjacent floor panels.

In the equipment unit floor sections, generally arranged in rows runningtransverse to the direction of the parallel beams, a group of seconddimensioned floor panels are placed side by side to form a baseunderneath said equipment units. Each second dimensioned panel spansbetween adjacent beams and rests thereon so that a pair of juxtaposedsecond dimensioned panels rest on a common beam. The underside of eachsecond dimensioned panel includes a threaded insert. A hat-shaped clampis saddled around lower edge and sides of the rectangular common beamand is alinged with the threaded inserts of the juxtaposed seconddimensioned panels. A cap screw fixedly connects the clamp to thejuxtaposed second dimensioned panel. In this manner, the row of clampedsecond dimensioned panels forms a rigid transverse support to preventshifting of the parallel spaced beams. Advantageously, only the seconddimensioned beams which are trapped underneath equipment units areclamped in place. The first dimensioned panels in nonequipment sectionsare freely removable and insertable for access to cabling and ductsunderneath the raised floor and for access to the clamps holding thetrapped panels. The clamped panels may be moved and rearranged to adaptto modifications in equipment unit placement.

DESCRIPTION OF THE DRAWING FIG. )1 depicts a perspective view of araised floor illustrative of the invention, with'parts broken away toillustrate construction;

FIG. 2 is a top view of a section of floor panels including a pair offloor panels which form the base for equipment units;

FIG. 3 is a front view of the adjacent panels of FIG. 2 taken alonglines 3-3 of FIG. 2;

FIG. 4 is an enlarged view of the clamping arrangements for floor panelswhich form the basevfor equipment units taken along lines 44 of FIG. 2;

FIG. 5 is an enlarged view of the pedestal arrangements in FIG. 2 takenalong lines 55 of FIG. 2; and

FIG. 6 is a side view taken along lines 66 of FIG. 2.

DETAILED DESCRIPTION 7 With reference to FIG. 1, equipment frames 6 aresupported at a predetermined distance above subfloor 9 on therectangular array of raised floor panels 3 and 4. The space underneaththe array of raised floor panels and above subfloor 9 permits anelectrical cable network to interconnect equipment units 6 and alsopermits ancillary apparatus servicing the equipment units to be placedbetween the raised floor and subfloor 9. Such ancillary units mayinclude pipes and air-conditioning elements such as air plenum space forequipment cooling.

The raised floor structure includes a plurality of spaced parallel beams1 running in one direction as shown in FIG. 1. Each beam comprises arectangular cross-section channel and is supported on a plurality ofequally spaced, vertically adjustable pedestals 2 which rest on thesubfloor. The raised floor itself comprises first dimensionedrectangular panels 4 arranged to form a flat surface in equipment accessareas and second dimensioned rectangular panels 3 underlying equipmentunits 6. Each first dimensioned panel 4 has opposite ends 10 resting ona pair of adjacent beams and the panel is freely insertable andremovable from the floor. Each second dimensioned panel 3 has oppositeends 11 resting on a pair of adjacent beams and is rigidly attached tosaid adjacent beams to provide transverse support for the adjacent beamswhereby shifting of the'parallel beams is prevented. The dimensions ofpanels 3 are adapted to fit underneath equipment 6. It is to beunderstood, however, that panels 3 may be of different dimensions andmay be. the same sizes as panel 4.

FIG. 2 shows a top view of first dimensioned panels 3a and 3b in aparticular equipment section of the raised floor along with adjacentfreely insertable and removable panels 4a and 4b. Panel 3a spans betweenand rests on beams la and 1b and panel 3b spans between and rests onbeams lb and 1c. Panel 30 is rigidly attached to beams 1a and 1b byunderside mounted clamp 71a and 71. Similarly panel 3b is rigidlyattached to adjacent beams lb and 1c by clamps 71 and 7 lb. Pedestals2a, 2b, and 2c underlie beams 1a, 1b, and 10, respectively.

FIG. 3 shows a front view of the raised floor structure of FIG. 2wherein the hat-shaped clamps 71a, 71, and 7 lb are shown attached tofloor panels 3a and 3b. Also shown in FIG. 3 are pedestals 2a, 2b, and2c, which pedestals support beams la, lb, and 1c, respectively. Theindividual pedestal structure and its connection arrangements to theunderlying beam are shown in FIG. 5.

Referring to FIG. 5, pedestal 2 comprises base plate 21 which rests onsubfloor 9. Lower column 23 extends upwardly from the center of baseplate 21 and the upper portion of column 23 includes externally threadedsection 25. Upper column 27 has a plate 29 fixedly attached to its upperend and said upper column includes a hollow lower end 31. Hollow end 31is slid over threaded section 25 of lower column 23 and rests on jacknut 33 which is threadily engaged with lower column section 25.Adjustment of the height of jack nut 33 provides a vertical levelingadjustment for the overlying raised floor. The leveling adjustmentaccommodates variations in the surface of subfloor 9. Cylindricalferrule 37 is press fitted on the outside of upper column 27 at itslower end 31 and rests on jack nut 33. Serrated grooves 35 in jack nut33 receive corresponding projections of ferrule 37 and the weight of theraised floor structure bearing on upper column 27 urges member 37 intogrooves 35 whereby the jack nut is constrained from rotation after theleveling adjustment has been completed.

Plate 29 on the top of upper column 27 includes a pair of holessymmetrically positioned on either side of column 27. Rectangular nuts41 inserted into the slotted low side of beam 1b and held in place bythe upwardly in-turned edges 43 of beam 1b are positioned over the holesin plate 29. The lower face of each rectangular nut includes serratedgrooves into which inturned edges 43 fit whereby nut 41 is preventedfrom rotating. Spring 45, resting against upper web 49 of beam 1b,forcibly urges nut 41 downwardly against the in-turned edges 43. Capscrews 47 are pushed through the holes in plate 29 and are threadedthrough nuts 41 to rigidly connect the pedestal to beam 1b. A side viewof the pedestal illustrating the positions of cap screws 47 and plate 29is shown in FIG. 6.

Each beam 1 has a rectangular cross-section as shown in FIG. andincludes closed top or web 49 and flanges 51 and 52. The flanges extendvertically downward and have upwardly in-turned edges 43 whereby thelower face of the beam includes a slot formed by inturned edges 43. Eachbeam may comprise sections of standard length whereby two or more end toend sections may be required in the raised floor structure of FIG. 1.Two beam sections may be joined over a pedestal by means of a U-shapedmember 28 as illustrated in FIG. 1. The U-shaped member includes a pairof holes on either side of upper column 27 which screw into rectangularnuts. The rectangular nut is inserted into each beam section. Thevertical sides of U-shaped member 28 are fitted tightly over flanges 51and 52 to rigidly connect the two beam sections. The U-shaped junctionmember replaces plate 29 in 'the pedestal shown in FIG. 5.

FIG. 5 also shows the mounting arrangements for a pair of seconddimensioned floor panels 4a and 4b on common beam 1b. A vinyl strip 64having a wedge projection 66 overlying the beam web center is attachedto web 49 and serves as a keying device for the proper positioning ofpanels 4a and 4b. Edge 61 of panel 4a and edge 62 of juxtaposed panel 4beach extend downwardly and inwardly so that the panels meet at theirupper edge points and are displaced by wedge 66 at their lower edgepoints. Panel 4a rests over one half of web section 49, while panel 4brests over the other half of web 49 whereby the loads on panels 4a and4b are transmitted to beam 1b and therefrom to the subfloor via thepedestals supporting beam 1b. Panels 4a and 4b, as well as all othersecond dimensioned panels, are freely insertable and removable from theraised floor through the use of suction devices or other means wellknown in the art adapted to verticalaly lift and lower the floor panels.

FIG. 4 illustrates the mounting and clamping arrangements for a pair offirst dimensioned panels 3a and 3b juxtaposed over common beam 1b. Panel3b includes an internally threaded insert 73 which is epoxied into ahole of suitable dimensions drilled into panel 3b a preset distance fromflange 52. Similarly, an insert is placed in panel 3a. Where the topplate of panel 3b is metallic, an insulating washer 75 is placed betweenthe metallic plate and insert 73 to electrically insulate the plate fromthe raised floor structure. In this way the raised floor surface iselectrically insulated from the beam and pedestal arrangement.

Hat-shaped clamp 71 of suitable width is saddled around beam 1b so thatit tightly conforms to flanges 51 and 52. The holes in the horizontalextending members of clamp 71 are aligned with threaded insert 73 underwasher 81, which washer has the same thickness as keying strip 64. Asimilar arrangement is provided for panel 3a. Cap screw 77 is threadedinto insert 73 through washer 79 whereby clamp 71 is rigidly connectedto panel 3b. Similarly, cap screw 85 is threaded into the insert ofpanel 3a to rigidly connect clamp 71 to panel 3a. Panels 3a and 3b arealso clamped to beams 1a and by clamps 71a and 71b, respectively, asshown in FIG. 2. In this way, the second dimensioned LII panels 3 form atransverse support to prevent beams 1 from shifting. Generally, seconddimensioned panels 3 are arranged in rows transverse to the direction ofbeams 1; and the rigid connection of panels 3 to beams 1 provides atransverse structural support for the raised floor. The freelyinsertable and removable panels 4 adjacent to the rows of panels 3provide access to the hatshaped clamps and the cap screws connectingpanels 3 to beams 1 and to the space beneath the raised floor.

In FIG. 1 each transverse row of clamped floor panels 3 form a base forequipment unit 6. Panel 3 includes a venting section 7 comprising arectangular array of apertures which serve as cooling air passageways.Air flows downward past one side of equipment unit 6, through ventingsection 7 of panel 3, and into the space between the raised floor andthe subfloor. This space functions as a return air duct for the coolingsystem arrangements not shown. Selected rows of freely insertable andremovable panels 4 also include venting sections 8 located in thecenters thereof. These venting sections provide air return passagewaysbetween adjacent rows of equipment unit 6 on the sides of the equipmentunits opposite to venting sections 7. The remaining rows of panels 4provide personnel access ways to the equipment units. Panels 4 in theseaccess rows do not include venting sections, since venting section 7 ofadjacent panels 3 suffices for cooling.

Equipment units 6 in FIG. 1 have a relatively narrow and high silhouettewhereby there is a possibility of accidental overturning. To avoid suchpossible overturning, the equipment units are fixedly attached to theunderlying panels 3. Internally threaded inserts are included in theupper sides of affixed panels 3 and the overlying equipment unit isbolted into place by bolts 91 which are threaded into inserts 90. Sincepanels 3 are rigidly attached to the space parallel beam structure, thebolting of equipment units to panels 3 provides adequate structuralsupport for the equipment units.

The described raised floor advantageously provides a smooth, flat,continuous surface in both equipment and equipment access areas. Thepanels trapped underneath equipment units are rigidly affixed to theunder lying spaced parallel beam structure whereby the beams arelaterally supported to prevent shifting. The affixing of'the beams tothe underside of the trapped panels eliminates any possibility ofelectrical grounds on the floor surface. All other floor panels arefreely insertable and removable so that access to the space underneaththe raised floor is readily obtained.

What is claimed is:

1. A raised floor for supporting equipment above 2 subfloor andproviding space underneath said equip ment for cabling and ancillaryapparatus comprising 2 plurality of beams in spaced parallel relation toeacl other running along one direction, a plurality of verti callyadjustable pedestals for supporting each beam, a plurality of freelyinsertable and removable first rectan gular floor panels each havingplanar edges and eacl spanning between a pair of adjacent beams andhavin; opposite ends resting on portions of said adjacen beam's, aplurality of second individually insertable ant removable rectangularfloor panels having planar edge underlying said equipment, each secondpanel span ning between a pair of adjacent beams and having op positeends resting on portions of said adjacent beams and means for fixedlysupporting said beams in sail spaced parallel relation comprising meansfor rigidlj attaching each pair of adjacent second panels to the commonbeam on which said pair of adjacent second panels rest.

2. A raised floor according to claim 1 wherein said attaching meanscomprises means for rigidly clamping the underside of each second panelto each of the adjacent beams on which its rests.

3. A raised floor according to claim 2 wherein each beam comprises arectangular cross-section channel having an upper web on which a pair ofjuxtaposed second panels rest and a pair of downwardly extendingvertical flanges, and said clamping means comprises a clamp conformedaround said flanges and including a horizontal extension underneath eachof said juxtaposed sec ond panels, each clamp horizontal extension beingrigidly but removably connected to the underside of the overlyingjuxtaposed second panel.

4. A raised floor for supporting a plurality of equipment units above asubfloor comprising a plurality of uniform cross-section channelsrunning in one direction in spaced parallel relation, a plurality ofvertically adjustable pedestals resting on said subfloor for supportingeach channel, a plurality of first rectangularly dimensionedindividually insertable and removable floor panels having planar edgeseach spanning a pair of adjacent channels and having opposite endsresting on portions of said adjacent channels in equipment accesssections, a plurality of second rectangularly dimensioned individuallyinsertable and removable floor panels each having planar edges and eachspanning a pair of adjacent channels and having opposite ends resting ona portion of each adjacent channel in sections underlying said equipmentunits, means for rigidly holding said channels in spaced parallelrelation comprising means for rigidly but removably attaching theundersides of each pair of juxtaposed second panels to tween a pair ofadjacent beams and having an opposite the channel on which saidjuxtaposed panels commonly rest.

5. A raised floor according to claim 4 further comprising means forrigidly attaching each equipment unit to the second panel underlyingeach equipment unit.

6. A raised floor according to claim 4 wherein said channel has arectangular cross section comprising an upper web on which said floorpanels rest and a pair of downwardly extending vertical flanges, andsaid attaching means comprises a hat-shaped clamp including a U-shapedsection saddled around said channel flanges and a pair of horizontalextensions each underneath one of said juxtaposed second floor panelsresting on said saddled channel, and means for rigidly but removablyconnecting the underside of each juxtaposed second panel to theunderlying clamp horizontal extenend resting on a portion of eachadjacent beam, said first panels being individually insertable andremovable and arranged side by side to form sections for accessing saidequipment units, a group of second rectangularly dimensionedindividually insertable and removable floor panels each having planaredges and each sized to span a pair of adjacent beams and having anopposite end resting on a portion of each adjacent beam, said secondpanels being placed side by side to form rows transverse to thedirection of said beams, said equipment units being supported on saidrows of second panels, and means for rigidly supportingsaid beams insaid spaced parallel relation comprising means for clamping theundersides of each pair of adjacent second panels to the beam on whichsaid adjacent panels commonly rest.

9. A raised floor according to claim 8 wherein each beam comprises anupper web section on which juxta posed panels rest and a pair ofvertical flanges extending downwardly from the edges of said websection, and said clamping means comprises a hat-shaped clamp includinga U-shaped section saddling said flanges and a horizontal sectionextending underneath each juxtaposed second panel resting on saidsaddled beam, each juxtaposed second panel resting on said saddled beamincluding an internally threaded insert, each clamp horizontal sectionhaving an aperture aligned with said threaded insert and a cap screw forthreadedly engaging said threaded insert to rigidly but removably affixsaid clamp to said juxtaposed second panel.

10. A raised floor according to claim 9 wherein said first panels andsaid second panels are arranged in alternating rows running transverseto the direction of said beams, each first panel being freely removablefor accessing the underside of said adjacent second panels.

11. A raised floor for supporting rearrangeable equipment above asubfloor comprising a plurality of stringers each running the length ofthe raised floor in substantially uniform spaced parallel relation, aline of spaced vertically adjustable pedestals resting on said subfloorfor supporting each stringer, a plurality of rectangularly dimensionedplanar edged floor panels, each panel spanning adjacent stringers andhaving opposite ends resting on portions of said adjacent stringers, andmeans for rigidly fixing said stringers in said spaced parallel relationcomprising means for rigidly but removably clamping the undersides ofselected floor panels to the stringer on which said selected panelsrest.

1. A raised floor for supporting equipment above a subfloor andproviding space underneath said equipment for cabling and ancillaryapparatus comprising a plurality of beams in spaced parallel relation toeach other running along one direction, a plurality of verticallyadjustable pedestals for supporting each beam, a plurality of freelyinsertable and removable first rectangular floor panels each havingplanar edges and each spanning between a pair of adjacent beams andhaving opposite ends resting on portions of said adjacent beams, aplurality of second individually insertable and removable rectangularfloor panels having planar edges underlying said equipment, each secondpanel spanning between a pair of adjacent beams and having opposite endsresting on portions of said adjacent beams, and means for fixedlysupporting said beams in said spaced parallel relation comprising meansfor rigidly attaching each pair of adjacent second panels to the commonbeam on which said pair of adjacent second panels rest.
 2. A raisedfloor according to claim 1 wherein said attaching means comprises meansfor rigidly clamping the underside of each second panel to each of theadjacent beams on which its rests.
 3. A raised floor according to claim2 wherein each beam comprises a rectangular cross-section channel havingan upper web on which a pair of juxtaposed second panels rest and a pairof downwardly extending vertical flanges, and said clamping meanscomprises a clamp conformed around said flanges and including ahorizontal extension underneath each of said juxtaposed second panels,each clamp horizontal extension being rigidly but removably connected tothe underside of the overlying juxtaposed second panel.
 4. A raisedfloor for supporting a plurality of equipment units above a subfloorcomprising a plurality of uniform cross-section channels running in onedirection in spaced parallel relation, a plurality of verticallyadjustable pedestals resting on said subfloor for supporting eachchannel, a plurality of first rectangularly dimensioned individuallyinsertable and removable floor panels having planar edges each spanninga pair of adjacent channels and having opposite ends resting on portionsof said adjacent channels in equipment access sections, a plurality ofsecond rectangularly dimensioned individually insertable and removablefloor panels each having planar edges and each spanning a pair ofadjacent channels and having opposite ends resting on a portion of eachadjacent channel in sections underlying said equipment units, means forrigidly holding said channels in spaced parallel relation comprisingmeans for rigidly but removably attaching the undersides of each pair ofjuxtaposed second panels to the channel on which said juXtaposed panelscommonly rest.
 5. A raised floor according to claim 4 further comprisingmeans for rigidly attaching each equipment unit to the second panelunderlying each equipment unit.
 6. A raised floor according to claim 4wherein said channel has a rectangular cross section comprising an upperweb on which said floor panels rest and a pair of downwardly extendingvertical flanges, and said attaching means comprises a hat-shaped clampincluding a U-shaped section saddled around said channel flanges and apair of horizontal extensions each underneath one of said juxtaposedsecond floor panels resting on said saddled channel, and means forrigidly but removably connecting the underside of each juxtaposed secondpanel to the underlying clamp horizontal extension.
 7. A raised flooraccording to claim 6 wherein each horizontal extension includes anapertured section, each juxtaposed second panel includes a threadedinsert overlying said apertured section of said clamp horizontalextension, and a cap screw threadily engaged with said panel threadedinsert to rigidly connect said clamp to said overlying juxtaposed panel.8. A raised floor for supporting a plurality of equipment units above asubfloor to provide space for cabling and ancillary apparatus beneaththe equipment units comprising a plurality of spaced parallel beams,each beam running the length of said raised floor, a plurality ofvertically adjustable pedestals attached to each beam and resting onsaid subfloor for supporting said beam, a group of first rectangularlydimensioned floor panels each having planar edges and sized to spanbetween a pair of adjacent beams and having an opposite end resting on aportion of each adjacent beam, said first panels being individuallyinsertable and removable and arranged side by side to form sections foraccessing said equipment units, a group of second rectangularlydimensioned individually insertable and removable floor panels eachhaving planar edges and each sized to span a pair of adjacent beams andhaving an opposite end resting on a portion of each adjacent beam, saidsecond panels being placed side by side to form rows transverse to thedirection of said beams, said equipment units being supported on saidrows of second panels, and means for rigidly supporting said beams insaid spaced parallel relation comprising means for clamping theundersides of each pair of adjacent second panels to the beam on whichsaid adjacent panels commonly rest.
 9. A raised floor according to claim8 wherein each beam comprises an upper web section on which juxtaposedpanels rest and a pair of vertical flanges extending downwardly from theedges of said web section, and said clamping means comprises ahat-shaped clamp including a U-shaped section saddling said flanges anda horizontal section extending underneath each juxtaposed second panelresting on said saddled beam, each juxtaposed second panel resting onsaid saddled beam including an internally threaded insert, each clamphorizontal section having an aperture aligned with said threaded insertand a cap screw for threadedly engaging said threaded insert to rigidlybut removably affix said clamp to said juxtaposed second panel.
 10. Araised floor according to claim 9 wherein said first panels and saidsecond panels are arranged in alternating rows running transverse to thedirection of said beams, each first panel being freely removable foraccessing the underside of said adjacent second panels.
 11. A raisedfloor for supporting rearrangeable equipment above a subfloor comprisinga plurality of stringers each running the length of the raised floor insubstantially uniform spaced parallel relation, a line of spacedvertically adjustable pedestals resting on said subfloor for supportingeach stringer, a plurality of rectangularly dimensioned planar edgedfloor panels, each panel spanning adjacent stringers and having oppositeends resting on portions of said adjacent stringers, and means forrigidly fixiNg said stringers in said spaced parallel relationcomprising means for rigidly but removably clamping the undersides ofselected floor panels to the stringer on which said selected panelsrest.